Chum is an old-fashioned, friendly word for a close friend or buddy. When someone calls you their chum, they mean you're good pals who enjoy spending time together. The word sounds a bit cheerful and casual, like you might hear in an old adventure story where two friends set off to explore together.

The word can also be used as a verb: to chum around with someone means to hang out together regularly, doing activities you both enjoy. Two students who always sit together at lunch and work on projects together might be described as chumming around.

Interestingly, chum has a completely different meaning in fishing: it refers to bits of fish or other bait that fishers throw into the water to attract larger fish. The scattered pieces of chum create a scent trail that draws fish to the area where the fisher wants to catch them. When sharks or other predators arrive to investigate the chum, they might find a baited hook waiting for them.